Epigenetic Silencing of miR-203 Upregulates SNAI2 and Contributes to the Invasiveness of Malignant Breast Cancer Cells.
Epigenetic Silencing of miR-203 Upregulates SNAI2 and Contributes to the Invasiveness of Malignant Breast Cancer Cells.
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DOI：
10.1177/1947601911429743
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发表时间：
2011-08-01
期刊：
影响因子：
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通讯作者：
Dong, Jin-Tang
中科院分区：
文献类型：
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作者：
Zhang, Zhiqian;Zhang, Baotong;Dong, Jin-Tang
人们越来越清楚，微小RNA（miRNA）在肿瘤发生和转移中发挥着重要作用。最近，据报道，miR-203 作为一种抑制性 microRNA，在肝细胞癌、前列腺癌、口腔癌和造血系统恶性肿瘤等不同恶性肿瘤中经常被沉默，但对其在乳腺癌发生中的潜在作用知之甚少。在这项研究中，我们发现在乳腺癌中，通过常规和实时 PCR 测量，miR-203 在原发性肿瘤和一些非转移性细胞系中上调，但在包括 BT549、Hs578T 和 MDA-MB-231 在内的转移性细胞系中显着下调。转移性乳腺癌细胞中 miR-203 的下调似乎是由其启动子的高甲基化引起的。从功能上讲，BT549和MDA-MB-231乳腺癌细胞系中miR-203的异位表达引起细胞周期停滞和细胞凋亡，并在体外抑制细胞侵袭和迁移。生物信息学分析预测 snail 同源物 2（SNAI2 或 SLUG）（一种促进细胞侵袭和肿瘤转移的转录因子）作为 miR-203 的靶标，并且通过对包含 miR-203 靶序列的 SNAI2 3' 非翻译区进行表达分析和荧光素酶报告基因测定来验证该预测。这些结果表明，在恶性乳腺癌细胞中，miR-203在表观遗传上被沉默，并且这种沉默至少部分通过上调SNAI2转录因子来促进肿瘤细胞生长和侵袭。
It has become increasingly clear that microRNAs (miRNAs) play important roles in tumorigenesis and metastasis. Recently, miR-203 was reported as a suppressor microRNA often silenced in different malignancies including hepatocellular carcinoma, prostate cancer, oral cancer, and hematopoietic malignancy, but little is known about its potential role in breast carcinogenesis. In this study, we found that in breast cancer, miR-203 was upregulated in primary tumors and some nonmetastatic cell lines but was significantly downregulated in metastatic cell lines including BT549, Hs578T, and MDA-MB-231, as measured by regular and real-time PCR. Downregulation of miR-203 in metastatic breast cancer cells appeared to be caused by hypermethylation of its promoter. Functionally, ectopic expression of miR-203 in BT549 and MDA-MB-231 breast cancer cell lines caused cell cycle arrest and apoptosis and inhibited cell invasion and migration in vitro. Bioinformatic analysis predicted the snail homolog 2 (SNAI2 or SLUG), a transcription factor that promotes cell invasion and tumor metastasis, as a target of miR-203, and the prediction was validated by expression analysis and luciferase reporter assay of the 3' untranslated region of SNAI2 that contains the miR-203 target sequences. These results suggest that in malignant breast cancer cells, miR-203 is epigenetically silenced, and the silencing promotes tumor cell growth and invasion at least in part by upregulating the SNAI2 transcription factor.